The Eastern and Western Christian churches use different methods of determining its date, and hence in most years Easter is celebrated on a different date in the two major branches of the Church.

Fixed date

It has been proposed that the first problem could be resolved by making Easter occur on a fixed date every year, or alternatively on a Sunday within a fixed range of seven dates. While tying it to one fixed date would serve to underline the belief that Easter commemorates an actual historical event, without an accompanying calendar reform it would also break the tradition of Easter always being on a Sunday, established by the First Ecumenical Council at Nicaea in AD 325 and by now deeply embedded in the liturgical practice and theological understanding of almost all Christian denominations.

The two most widespread proposals for fixing the date of Easter would set it on either the second Sunday in April (8th to 14th), or the Sunday after the second Saturday in April (9th to 15th). In both schemes, account has been taken of the fact that—in spite of the many difficulties in establishing the dates of the historical events involved—many scholars attribute a high degree of probability to FridayApril 7, 30, as the date of the crucifixion of Jesus, which would make April 9 the date of the Resurrection. Many churches, including the Roman Catholic Church, have stated that they have no objection in principle to fixing the date of Easter in this way, but no serious discussions have yet taken place on implementing such a change.

This reform has not been implemented. It would have relied mainly on the co-operation of the Eastern Orthodox Church, since the date of Pascha (Easter) would change for them immediately; whereas for the Western churches the new system would not differ from that currently in use until 2019. However, Eastern Orthodox support was not forthcoming, and the reform failed. The much greater impact that this reform would have had on the Eastern churches in comparison with those of the West led some Orthodox to suspect that the WCC's decision was an attempt by the West to impose its viewpoint unilaterally on the rest of the world under the guise of ecumenism.

A virtually identical astronomical rule for Easter was proposed by the 1923 synod that also proposed the Revised Julian calendar: Easter was to be the Sunday after the midnight-to-midnight day at the meridian of the Church of the Holy Sepulchre in Jerusalem (35°13'46"E or UT+2h20m55s for the large dome) during which the first full moon after the vernal equinox occurs. Although the instant of the full moon must occur after the instant of the vernal equinox, it may occur on the same day. If the full moon occurs on a Sunday, Easter is the following Sunday. Although the Revised Julian calendar was adopted by many Orthodox Churches, all rejected the astronomical rule for Easter and continue to use the Julian calendar to determine the date of Easter (except for the Finnish Orthodox Church, which now uses the Gregorian Easter).